The present invention relates to a fiber laser device that can measure the power of output light, and more specifically to a fiber laser device suited to the case where light of great power is emitted.
Since a fiber laser device has an excellent light gathering property and a high power density and obtains light that is formed in a small beam spot, the fiber laser device is used in various fields such as a laser processing field and a medical field.
In such a fiber laser device, since the power of output light affects processing quality, it is preferable to measure the power of output light. The fiber laser device generally includes a monitor unit inside the device in order that it is enabled to know the power of output light without directly measuring the power of output light by a user.
Patent Document 1 below describes an optical fiber amplifier in which the output light is branched from a rare earth doped fiber and measured. A method for measuring the power of output light used in this optical fiber amplifier is also used in fiber laser devices.
[Patent Document 1] JP-A-H05-206555